TMJ syndrome, and related joint diseases, are manifested by the formation of relatively hard tissues entrapped in the synovial fluid adjacent to said joint. One mode of treatment is by the removal of the scar tissue located inside the TMJ. The scar tissue may be formed by acute trauma (e.g. a car accident) or chronic trauma (e.g. clenching or grinding), due to synovitis, or due to lack of mobility. Such a hard tissue in the temporomandibular joint usually results in a limitation of jaw opening. Treatment requires “passive motion” physical therapy, and surgery.
Joint arthroscopy, mostly in the knee but also in the shoulder, ankle and other small body joints, is one of the most common orthopedic surgical procedures. Arthroscopy is performed for a range of indications such as torn or damaged meniscus (menisectomy), chondramalacia (cartilage debridment), arthritis (synovectomy), torn or damaged ligament (tendon excision/resection) and other. Arthroscopy is performed as an out-patient procedure, usually under local anesthesia, by inserting an endoscope into the knee and insufflating the knee with saline to enable view and access to the different anatomical sites in the joint. Surgery is usually performed with powered mechanical tools such as shavers and burrs. Surgical tools are inserted into the patient's knee through small, 5 mm, incisions (ports). The limitations of these mechanical tools are their size (typically 4 mm diameter) which often blocks the view of a region of interest in the body, causes undesirable tissue removal and restricts access to tight joint spaces such as in the posterior horn.
Recently an RF technique (Coblation™, Arthrocare) has been introduced for arthroscopy. However, an instrument size (about 4 mm diameter), as well as surrounding necrosis, is still a limitation.
Attempts to introduce lasers to arthroscopy began about 20 years ago based on the potential of lasers to afford higher precision, no mechanical trauma and access to tight spaces due to thin delivery fibers. The first laser introduced in the late 80's was the CO2 laser, delivered through hollow ceramic tubes. This laser was able to ablate all non-bony joint tissues with acceptable precision and surrounding necrosis. However, this laser could not be used with the regular saline insufflation of the joint, but required gas insufflation. While gas insufflation of the joint is technically possible, it entails a risk of gas emphysema and is not a standard technique. Therefore, the use of this laser in arthroscopy remained in the hands of very few arthroscopists. In the early 90's, a second attempt was made with the NdYAG laser in the contact mode. This technique was soon abandoned due to deep tissue necrosis and breakage of the fibers inside the knee.
The only laser type that was, in 90's, found applicable for arthroscopy (as well as discectomy) is Holmium laser. Later, in 1996, it was found that Holmium radiation based arthroscopy treatment might result in osteonecrosis. More specifically, a Holmium laser commonly used to repair knee joints has shown two contradicting effects: while being able to repair the knee in the short term, it caused hidden damage to surrounding cells and worsening the injury in the long term.
A recent advance in oral and maxillofacial surgery includes the delivery of laser energy through an arthroscope to the temporomandibular joint area in order to remove the hard tissue, which procedure replaces open joint surgery. Typical treatment includes administration of Holmium laser to the joint area. The procedure is carried out at an ambulatory care center, with discharge within several hours of the procedure. Most patients are back to work within 4-5 days. The conservative nature of laser debridement of adhesions is a significant aid in the treatment of the problems associated with TMJ dysfunction.
U.S. Pat. No. 5,582,190 to Slavin et al. teaches a Holmium-laser-based arthroscopic method for relieving symptoms caused by temporomandibular joint disorder in a patient. Their method is based on the following fourteen steps: (a) injecting a solution of lidocaine and epinephrine into a superior joint space of a temporomandibular joint of a patient, thereby providing distention thereof; (b) making a first vertical incision anterior to the posterior aspect of the tragus of the ear of the patient; (c) making a second vertical incision anterior to the first incision and below a line from the posterior aspect of the tragus of the ear to the lateral canthus of the orbit; (d) perforating the superior joint space bluntly with a first cannula and a first blunt trocar inserted into the first vertical incision and a second cannula and a second blunt trocar inserted into the second vertical incision; (e) advancing the first and the second cannula; (f) removing the first and the second trocar; (g) placing an arthroscope through the first vertical incision, allowing direct visualization of the joint; (h) placing a switching stick through the second vertical incision; removing the second cannula; (i) providing a dual-channel cannula having a distal end, a proximal end, a first and a second channel, each extending from the proximal to the distal end; (j) inserting the dual-channel cannula over the switching stick into an anterior recess of the superior compartment of the joint; (k) removing the switching stick; (l) locking the arthroscope into the first channel of the dual-channel cannula; (m) inserting an optical fiber into the second channel of the dual-channel cannula, the optical fiber for channeling radiation from a holmium laser; and (n) performing a desired surgical procedure within the joint space. According to Slavin's invention, the first and a second 2.0 mm cannula and a first and a second blunt trocar are used.
An additional example of removing hard tissues from relative soft organs is the pulverizing of physiological stones, and more particularly, the removal of calcium stones from the salivary ducts. The mechanism of salivary stone formation is unclear, but seems to be multi-factorial. About 1% of people suffer from salivary stones. Most stones form in the sub-mandibular gland (85%) and the remainder in the parotid (15%).
The elimination of stones from the body, such as kidney stones and gallstones has been known for decades. Lithotripsy is the pulverization and removal of urinary or other calculi using a lithotripter. A lithotripter is capable of fragmenting kidney stones with ultrasound waves. The majority of patients (85-90%) are rendered symptom free and in 30-50% of cases, the stones are completely cleared from the salivary glands. The remainder retains some stone debris.
There has been an increased interest in pulsed erbium lasers operating in the 3-μm region for tissue ablation. These lasers advantageously emit wavelengths very highly absorbable by tissue water, thus would cause minimal damage to surrounding tissues.
The range of clinical applications for these lasers is continually expanding due to the controllable qualities of cutting, removal and pulverization of soft and hard tissues, which make these wavelengths attractive for minimally invasive surgical treatments. However, as most clinical treatments in orthopedics, angioplasty, ophthalmology, or lithotripsy, are performed in a liquid environment, often in a non-contact mode, most of the laser energy is absorbed in the water and little is left for tissue ablation.
Erbium is a metallic element of the rare-earth group. Erbium is always found in combination with yttrium, another rare earth, and the ore is mined in the form of yttrium-aluminum-garnet (YAG).
The Erbium YAG laser emits a 2940 nm wavelength beam of light. Due to the extremely strong absorption of its 3 μm-radiation in biological tissue, the erbium laser has become a very useful and precise tool in surgery. The resulting penetration depths are around 2-3 μm and thus offer a minimal invasive and precise ablation of tissue.
Holmium lasers have an advantage when transmission of the laser beam over longer distances is required, such as when transmitting the energy from the apparatus to the kidneys, while Erbium lasers are effective for shorter distances as their energy can not be transmitted through conventional silica fibers.
Erbium laser frequencies are highly effective for the treatment of hard tissues, because of the ability to pulverize these hard tissues. Consequently, Erbium YAG lasers are used in dentistry as substitute for the painful, noisy drill, especially for clearing the areas of tooth decay.
The use of Erbium lasers for laser lithotripsy of salivary stones is unknown in the art. The idea of using Erbium lasers for endoscopic lithotripsy was initiated in 2001, but not for the salivary glands. Erbium lasers have been researched for urology for the removal of kidney stones (Chang et al., Journal of Urology, 168:436-441, (2002)), and are well known for drilling of teeth.
U.S. Pat. No. 6,375,651 to Grasso III et al. discloses a medical device, which requires a suction conduit, and an energy-transmitting conduit wherein at least some of the transmitted energy is directed to the distal region of the suction conduit. The said device includes an optical apparatus for directing the energy. The device has applications in lithotripsy and tissue-removal in a patient. Ho:YAG laser was claimed to be useful for such procedures. The inventors also suggested to utilize lasers based on thulium (Th), Erbium:yttrium-aluminum-garnet (Er:YAG) (190 to 350 μm), HF, DF, CO, and CO2 in the mid-infrared region, and excimer lasers in the ultraviolet region. However the technology disclosed in this publication is unsuitable for pulverizing stones in the salivary ducts because suction is not possible in physiological conduits as small as the salivary ducts, which have a maximal diameter of 3 mm.
It is well acknowledged that introduction of a suction means in the manner defined in this patent will promptly and irreversibly collapse the fragile salivary duct and this is probably the reason why the treatment of such small-diameter ducts is not defined specifically as embodiments of this patent.
U.S. Pat. No. 6,395,000 to Mitchell et al. discloses a medical laser system for ablating biological material. The system also includes an Er:YAG laser useful for various ophthalmic procedures, including capsulotomies, sclerostomies, excision of pupillary membranes, cutting of vitreous bands and iris margin. The system is described by the inventors to be also useful for a variety of urinary organ procedures such as kidney wall modification, stone (calculi) fragmentation and removal in the kidney, gall bladder and ureter (lithotripsy), transurethral incision of the prostate, prostatectomy, ureter lesion removal, vasal tissue removal, nephrectomy, vasovasotomy and lymph node modification. Moreover, the system supposed also to be useful for opening strictures in the aorta, modifying vessels at an aneurysm, for clearing vessels (angioplasty) and for removing clots. However, the system as described in aforementioned Mitchell's patent was not found useful for pulverizing stones in the salivary gland ducts.